Allow user specified python interpreter

src/ansible_dev_environment/arg_parser.py

@@ -34,6 +34,7 @@
     "ansi": "NO_COLOR",
     "ansible_core_version": "ADE_ANSIBLE_CORE_VERSION",
     "isolation_mode": "ADE_ISOLATION_MODE",
+    "python": "ADE_PYTHON",
     "seed": "ADE_SEED",
     "uv": "ADE_UV",
     "venv": "VIRTUAL_ENV",
@@ -227,6 +228,13 @@ def parse() -> argparse.Namespace:
         help="Install editable.",
     )
 
+    install.add_argument(
+        "-p",
+        "--python",
+        dest="python",
+        help="Python interpreter to use for the virtual environment. A version. name or path can be provided. If not provided, the python interpreter for the current process will be used.",
+    )
+
     install.add_argument(
         "--seed",
         action=argparse.BooleanOptionalAction,

src/ansible_dev_environment/config.py

@@ -43,6 +43,7 @@ def __init__(
         self._output: Output = output
         self.python_path: Path
         self.site_pkg_path: Path
+        self.specified_python: str | Path | None = None
         self.venv_interpreter: Path
         self.term_features: TermFeatures = term_features
 
@@ -164,34 +165,53 @@ def _set_interpreter(
         self,
     ) -> None:
         """Set the interpreter."""
-        if self.uv_available:
-            venv_cmd = "uv venv --seed --python-preference=system"
+        self._locate_python()
+        if self.specified_python is None:
+            venv_cmd = (
+                "uv venv --seed --python-preference=system"
+                if self.uv_available
+                else f"{sys.executable} -m venv"
+            )
         else:
-            venv_cmd = f"{sys.executable} -m venv"
+            venv_cmd = (
+                f"uv venv --seed --python-preference=system --python {self.specified_python}"
+                if self.uv_available
+                else f"{self.specified_python} -m venv"
+            )
+
+        if self.venv.exists() and self.specified_python:
+            err = "User specified python cannot be used with an existing virtual environment."
+            self._output.critical(err)
+            return  # pragma: no cover # critical exits
+
+        if not self.venv.exists() and not self._create_venv:
+            err = f"Cannot find virtual environment: {self.venv}."
+            self._output.critical(err)
+            return  # pragma: no cover # critical exits
 
         if not self.venv.exists():
-            if self._create_venv:
-                msg = f"Creating virtual environment: {self.venv}"
-                command = f"{venv_cmd} {self.venv}"
-                if self.args.system_site_packages:
-                    command = f"{command} --system-site-packages"
-                    msg += " with system site packages"
-                self._output.debug(msg)
-                try:
-                    subprocess_run(
-                        command=command,
-                        verbose=self.args.verbose,
-                        msg=msg,
-                        output=self._output,
-                    )
-                    msg = f"Created virtual environment: {self.venv}"
-                    self._output.info(msg)
-                except subprocess.CalledProcessError as exc:
-                    err = f"Failed to create virtual environment: {exc}"
-                    self._output.critical(err)
-            else:
-                err = f"Cannot find virtual environment: {self.venv}."
+            msg = f"Creating virtual environment: {self.venv}"
+            command = f"{venv_cmd} {self.venv}"
+            if self.args.system_site_packages:
+                command = f"{command} --system-site-packages"
+                msg += " with system site packages"
+            self._output.debug(msg)
+            try:
+                subprocess_run(
+                    command=command,
+                    verbose=self.args.verbose,
+                    msg=msg,
+                    output=self._output,
+                )
+                msg = f"Created virtual environment: {self.venv}"
+                if self.specified_python:
+                    msg += f" using {self.specified_python}"
+                self._output.note(msg)
+            except subprocess.CalledProcessError as exc:
+                err = f"Failed to create virtual environment: {exc.stdout} {exc.stderr}"
                 self._output.critical(err)
+                return  # pragma: no cover # critical exits
+
         msg = f"Virtual environment: {self.venv}"
         self._output.debug(msg)
         venv_interpreter = self.venv / "bin" / "python"
@@ -239,3 +259,44 @@ def _set_site_pkg_path(self) -> None:
         self.site_pkg_path = Path(purelib)
         msg = f"Found site packages path: {self.site_pkg_path}"
         self._output.debug(msg)
+
+    def _locate_python(self) -> None:
+        """Locate the python interpreter.
+
+        1) If not user provided default to system
+        2) If it is a path and exists, use that
+        3) If it starts with python and uv, use that
+        4) If it starts with python and pip, use that
+        5) If it is a version and uv, use that
+        6) If it is a version and pip, and found, use that
+
+        """
+        python_arg = getattr(self.args, "python", None)
+        if not python_arg:
+            return
+
+        if Path(python_arg).exists():
+            self.specified_python = Path(python_arg).expanduser().resolve()
+        elif python_arg.lower().startswith("python"):
+            if self.uv_available:
+                self.specified_python = python_arg
+            elif path := shutil.which(python_arg):
+                self.specified_python = path
+            else:
+                msg = f"Cannot find specified python interpreter. ({python_arg})"
+                self._output.critical(msg)
+                return  # pragma: no cover # critical exits
+        else:
+            possible = f"python{python_arg}"
+            if self.uv_available:
+                self.specified_python = possible
+            elif path := shutil.which(possible):
+                self.specified_python = path
+            else:
+                msg = f"Cannot find specified python interpreter. ({possible})"
+                self._output.critical(msg)
+                return  # pragma: no cover # critical exits
+        self._output.debug(
+            f"Using specified python interpreter: {self.specified_python}",
+        )
+        return

tests/integration/test_user_python.py

@@ -0,0 +1,111 @@
+"""Test multiple variants of python version."""
+
+from __future__ import annotations
+
+import sys
+
+from pathlib import Path
+
+import pytest
+
+from ansible_dev_environment.cli import main
+
+
+def generate_pythons_uv() -> list[str]:
+    """Generate a list of python versions.
+
+    Returns:
+        List of python versions
+    """
+    pythons = ["python3"]
+    version = sys.version.split(" ", maxsplit=1)[0]
+    pythons.append(version)
+    pythons.append(f"python{version}")
+    major_minor = version.rsplit(".", 1)[0]
+    pythons.append(major_minor)
+    major, minor = major_minor.split(".")
+    one_less = f"{major}.{int(minor) - 1}"
+    pythons.append(one_less)
+    sys_path = str(Path("/usr/bin/python3").resolve())
+    pythons.append(sys_path)
+    return pythons
+
+
+@pytest.mark.parametrize("python", generate_pythons_uv())
+def test_specified_python_version_uv(
+    python: str,
+    capsys: pytest.CaptureFixture[str],
+    tmp_path: Path,
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    """Build the venv with a user specified python version.
+
+    Args:
+        python: Python version
+        capsys: Capture stdout and stderr
+        tmp_path: Temporary directory
+        monkeypatch: Pytest monkeypatch
+    """
+    venv_path = tmp_path / ".venv"
+    monkeypatch.setattr(
+        "sys.argv",
+        [
+            "ade",
+            "install",
+            f"--venv={venv_path}",
+            f"--python={python}",
+        ],
+    )
+    with pytest.raises(SystemExit):
+        main()
+
+    captured = capsys.readouterr()
+    venv_line = [
+        line for line in captured.out.splitlines() if "Created virtual environment:" in line
+    ]
+    assert venv_line[0].endswith(python)
+
+
+def generate_pythons_pip() -> list[str]:
+    """Generate a list of python versions.
+
+    Returns:
+        List of python versions
+    """
+    pythons = ["python3"]
+    version = sys.version.split(" ", maxsplit=1)[0]
+    major_minor = version.rsplit(".", 1)[0]
+    pythons.append(major_minor)
+    sys_path = str(Path("/usr/bin/python3").resolve())
+    pythons.append(sys_path)
+    return pythons
+
+
+@pytest.mark.parametrize("python", generate_pythons_pip())
+def test_specified_python_version_pip(
+    python: str,
+    capsys: pytest.CaptureFixture[str],
+    tmp_path: Path,
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    """Build the venv with a user specified python version.
+
+    Args:
+        python: Python version
+        capsys: Capture stdout and stderr
+        tmp_path: Temporary directory
+        monkeypatch: Pytest monkeypatch
+    """
+    venv_path = tmp_path / ".venv"
+    monkeypatch.setattr(
+        "sys.argv",
+        ["ade", "install", f"--venv={venv_path}", f"--python={python}", "--no-uv"],
+    )
+    with pytest.raises(SystemExit):
+        main()
+
+    captured = capsys.readouterr()
+    venv_line = [
+        line for line in captured.out.splitlines() if "Created virtual environment:" in line
+    ]
+    assert venv_line[0].endswith(python)

tests/unit/test_config.py

@@ -7,6 +7,7 @@
 import json
 import shutil
 import subprocess
+import sys
 
 from pathlib import Path
 from typing import TYPE_CHECKING, Any
@@ -669,3 +670,75 @@ def test_uv_disabled(monkeypatch: pytest.MonkeyPatch, capsys: pytest.CaptureFixt
     output = capsys.readouterr()
     assert "uv is disabled" in output.out
     assert cli.config.venv_pip_install_cmd.endswith("/bin/python -m pip install")
+
+
+def test_venv_exist_python_specified(
+    monkeypatch: pytest.MonkeyPatch,
+    capsys: pytest.CaptureFixture[str],
+    tmp_path: Path,
+) -> None:
+    """Test that if the venv exists and python is specified, exit.
+
+    Args:
+        monkeypatch: Pytest fixture.
+        capsys: Pytest fixture for capturing output.
+        tmp_path: Pytest fixture for temporary directory.
+    """
+    version = sys.version.split(" ", maxsplit=1)[0]
+    venv_path = tmp_path / ".venv"
+    monkeypatch.setattr(
+        "sys.argv",
+        ["ansible-dev-environment", "install", "--python", version, "--venv", str(venv_path)],
+    )
+
+    venv_path.mkdir(parents=True, exist_ok=True)
+
+    cli = Cli()
+    cli.parse_args()
+    cli.init_output()
+    cli.config = Config(
+        args=cli.args,
+        output=cli.output,
+        term_features=cli.term_features,
+    )
+    with pytest.raises(SystemExit) as exc:
+        cli.config.init()
+    assert exc.value.code == 1
+
+    output = capsys.readouterr()
+    assert "cannot be used" in output.err
+
+
+@pytest.mark.parametrize("python", ("python1000", "1000", "not_python"))
+def test_pip_missing_python(
+    python: str,
+    monkeypatch: pytest.MonkeyPatch,
+    capsys: pytest.CaptureFixture[str],
+) -> None:
+    """Test if uv is disabled and python cannot be found, exit.
+
+    Args:
+        python: Python version
+        monkeypatch: Pytest fixture.
+        capsys: Pytest fixture for capturing output.
+    """
+    monkeypatch.setattr(
+        "sys.argv",
+        ["ansible-dev-environment", "install", "--python", python, "--no-uv"],
+    )
+
+    cli = Cli()
+    cli.parse_args()
+    cli.init_output()
+    cli.config = Config(
+        args=cli.args,
+        output=cli.output,
+        term_features=cli.term_features,
+    )
+    with pytest.raises(SystemExit) as exc:
+        cli.config.init()
+    assert exc.value.code == 1
+
+    output = capsys.readouterr()
+    assert "Cannot find specified python interpreter." in output.err
+    assert python in output.err